Total Loss issue; backfiring...

[BombThreat]

My boat has been running fine for the 3-4 hours ive run the setup this year. Although once in a while it would backfire if I just flipped the MSD power switch on and left the boat alone... It would just pop once and thats it. Did that on 3-4 separate occasions.

But last time I had the boat on the lake it would running just fine, blipping it around and then it just all of a sudden bogged and died. It would only backfire when trying to start it or running for 5-10feet and thats it. I checked the flywheel to see if it stripped and its fine, swapped out the pickup and thats not it. Checked the reeds and thats not it. Eliminated the start/stop wires and thats not it.

What else could it be?

Its a Analog system btw

 

[Waternut]

Did you double check your timing with a light? What kind of timing are your running?

 

[ATS_Aaron]

Yep. Welcome to my world.

28 degrees initial advance literally blew my cases apart from the backfire.

25 degrees starts fine and actually pulls harder.

Aaron

 

[Winter X2]

This happened to me before. The ski backfired because my timing was off. The flywheel came loose and the magnet was way off from TDC. I would double check that your stator plate didn't move. even a 1/4 inch can really throw things off. Check it all twice.. probably something really obvious. Good luck.

 

[BombThreat]

Thanks guys, Im running 28deg static with 5000 low, 5/1000 retard and 8000 high.


The plate was as tight as can be when i took it off to check the pickup, but ill get in there again and make sure the timing is where its got to be... I'll probally try lowing it like you said ATS.

Thanks again

-Scott

 

[Waternut]

Don't rule out the brain acting funny though. That's why I asked if you double checked with a timing light.

 

[CARBONX2]

I've had it with a bad brain, idled and low revs fine, past 3000rpm it backfired, swopped in another brain with the same settings and it ran fine.

 

[SUPERTUNE]

Welcome to the old school of MSD ANALOG TL ignitions! Yes, retarding the timing might help some... but not usually.
If the engine has stopped with the pick up magnet anywhere by the trigger, as soon as you power up the switch, the cdi fires! If there's any fuel around in the chamber... BOOM is what you get.
The only other thing that helped us with this problem is to crank the engine with the starter first for 10 seconds and purge the fuel charge caught in the cylinder and exhaust. Now turn on the ignition switch as soon as you stop cranking, then start, we didn't get as many backfires by using this starting method.
That's one of many reasons I won't use them as they don't have the new features like the electric start mode and 20* degree start retard that the new multichannel digital TL have now. This is how MSD has fixed these older problems.

 

[madscientist]

i had a similar problem just before my and coil died

 

[Waternut]

Welcome to the old school of MSD ANALOG TL ignitions! Yes, retarding the timing might help some... but not usually.
If the engine has stopped with the pick up magnet anywhere by the trigger, as soon as you power up the switch, the cdi fires! If there's any fuel around in the chamber... BOOM is what you get.
The only other thing that helped us with this problem is to crank the engine with the starter first for 10 seconds and purge the fuel charge caught in the cylinder and exhaust. Now turn on the ignition switch as soon as you stop cranking, then start, we didn't get as many backfires by using this starting method.
That's one of many reasons I won't use them as they don't have the new features like the electric start mode and 20* degree start retard that the new multichannel digital TL have now. This is how MSD has fixed these older problems.

That explains why I blew up 3 fiberglass waterboxes in two different ski's with my single channel TL systems. The end all fix for me was metal waterboxes but good to know what the real cause was.

 

[2XLR8]

I don't think the 28 degree timing has anything to do with it because if it did it would have done it right from the start. I think the new digital ignitions rotate a few times before sparking this allows residual fuel vapors to be pushed back. Yes if the engine stops near the pickup it will even occasionally fire just by turning the ignition switch on. This same problem arises with defective wire contacts at the pickups. Just cranking the engine will cause a break in the wire and at the right time kaboom and if you have fiberglass water box like in pre 96 models it could break apart in pieces